The image in the PDF file that I downloaded looks dark on Adobe Acrobat Reader

If the image in your PDF file looks dark when viewed on Adobe Acrobat Reader, it is because of a particular setting. To resolve this issue, follow the steps below:

1. Open your PDF file on Adobe Acrobat Reader.
2. Click on Edit.
3. Click on Preferences.
4. Select Page Display from the list of categories.
5. Under Rendering, make sure that the check box beside Enhance thin lines is unchecked.
6. Click OK.
7. Try reopening your PDF file again. The image in the PDF file should be fine now.